A Double lane change event drives the vehicle through a lane change and a return to
lane maneuver, attempting to follow the centerline of the defined lane.
You can define the speed of the lane change, along with the lane dimensions. The Altair
Driver model is used to maintain speed throughout the event. The event supports right and
left lane changes.
The double lane change event is supported by the Cars & Small Trucks, Heavy Trucks, and
Two-Wheeler vehicle libraries. Automated output reports are available to plot the
results.
The event does not have specific metrics associated with it. A lane change is typically
used as a subjective evaluation test. The double lane change event follows the ISO
3888-2-2011 - Passenger cars Test track for a severe lane-change maneuver and the NATO
Allied Vehicle Testing Publication AVTP: 03-160 Sep. 1991. Figure 1. Double Lane Change - Path
Parameters
Parameter Name
Description
Units
Describes the Length, Velocity, and Acceleration units.
Length (Model, m, ft)
Velocity (Model, m/s, km/h, mph).
Acceleration (Model, m/s2, g’s).
Lateral offset
Offset distance of the double lane change.
Length- Section 1
Length of the initial straight section of road.
Length- Section 2
Longitudinal length of the initial lane change section of road.
Length- Section 3
Length of the center straight section of road.
Length- Section 4
Length of the second lane change section of road.
Length- Section 5
Length of the recovery section of road.
Velocity
The initial speed of the vehicle.
Turn direction
Direction the vehicle turns during the event (as seen by the driver).
Controller Settings
Non-leaning events (Cars/Trucks)
LONGITUDINAL – TRACTION CONTROLLER SETTINGS
Use additional control: Enables the additional feedback control for the traction
control. The gains for the controller can be edited by toggling this check
box.
Kp
Proportional gain for the feedback PID controller
Ki
Integral gain for the feedback PID controller
Kd
Derivative gain for the feedback PID controller
LATERAL – STEERING CONTROLLER SETTINGS
Altair Driver uses Feedforward steering controller for non-leaning vehicles like
Cars and Trucks. The following settings can be edited by the user.
Look ahead time
Look ahead time for the feedforward model to evaluate future states
of the vehicle
Prediction step size
Maximum step size, used by the Driver feedforward steering
model
Use additional control: Enables the additional feedback control for the traction
control. The gains for the controller can be edited by toggling this check
box.
Kp
Proportional gain for the feedback PID controller
Ki
Integral gain for the feedback PID controller
Kd
Derivative gain for the feedback PID controller
LATERAL – STEERING CONTROLLER SETTINGS
The Lean PID and Lateral Error PID controllers only apply to leaning vehicles
(for example, motorcycles and scooters).
Steer control: Control mode for
steering can be switched between ‘MOTION’ and ‘TORQUE’
Lean control
The Lean PID takes as input a demand lean angle and outputs front fork
(steering) angle. For open loop events the lean angle demand is a function
of time. For closed loop path following events the demand lean angle is
computed based on the vehicle speed and the path curvature with a correction
for lateral path error.
Kp
Proportional gain for the lean controller
Ki
Integral gain for the lean controller
Kd
Derivative gain for the lean controller
Lateral error control
The Lateral Error PID takes as input the predicted lateral path error and
outputs an increment to the demanded lean angle. The lateral error is
computed by predicting the vehicle’s lateral position relative to the path
by the look ahead time in the future. The Lateral Error PID acts to lean the
vehicle toward the path.
Look ahead time
Look ahead time for the feedforward model to evaluate future
states of the vehicle
Kp
Proportional gain for the lateral error controller
Use the signal settings to set minimum, maximum, smooth frequency and initial values for
Steering, Throttle, Brake, Gear, and Clutch signals output by the driver.
The smoothing frequency is used to control how fast the Driver changes signals. Only closed
loop control signals from the Driver are smoothed. Open loop signals are not smoothed.
Road Settings
Three options are available to specify the road in the event, Flat Event, Road File, and Tires.
Flat Road
Uses a flat smooth road for the event with no required road file.
When the Flat
Road is selected, the Graphics Setting option is available with the following
parameters:
View path centerline: Enables the visualization of the event path.
This check box is disabled for open loop events without a path.
View grid graphics: Enables the visualization of the road grid graphics.
When view grid graphics check box is toggled, road grid parameters can be
edited in the Grid Settings tab.
Grid length
Defines the length of the road. Enter a positive value in the
model units.
Grid Width
Defines the width of the road. Enter a positive value in the
model units.
Grid X offset
Gives a distance offset to the road graphics in the longitudinal
direction. Enter a positive value in the model units.
Grid Y offset
Gives a distance offset to the road graphics in the lateral
direction. Enter a positive value in the model units.
Road File
The road file option enables the selection of a road file to be used in the event.
Using this option, all tires in the model consider the event specified road file
instead of the file included in the tire entities.
Tires
Using Tire as road selection option, the road file specified in the tire entity is
used in the events simulation.
Automated Output Report
The list of outputs present in a Double lane change event report are as follows:
